Defoliation of tree fruit nursery stock with CGA-15281

Abstract

In 2 test years, the ethylene-releasing agent CGA-15281 [2-chloroethyl-methylbis (phenylmethoxy) silane] had a significant effect on leaf abscission of budded and seedling fruit trees. Several apple cultivars, ‘Bartlett’ pear, and seedlings of apple, pear and cherry were treated with single or double applications (at 4-day intervals) of 1000, 1500 or 2000 mg l −1. Except for apple and pear seedlings, the 1500 mg l −1 concentration produced nearly 100% abscission, with significantly less effect from 1000 mg l −1. When trees were replanted after storage (done the second year only), 2–15 cm of shoot dieback was evident on all treatments with ‘Rome’ apple, and delayed bud break was evident on most treatments with ‘Bartlett’ pear. The other plants were much less negatively affected (‘Redspur Delicious’, ‘Goldspur’ and ‘Nured Jonathan’ apples; pear seedlings) or appeared to be unaffected (‘Redchief Delicious’ apple; apple and cherry seedlings).